JP3016964B2 - Automatic fire extinguisher for cooker - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic fire extinguisher for cookers which automatically extinguishes a fire when a detected temperature exceeds a predetermined temperature in order to prevent water from evaporating in a cooked dish or the like. About.

[0002]

2. Description of the Related Art As a technique of this type for automatically extinguishing a cooker, there is a technique disclosed in Japanese Patent Publication No. 63-67106, for example. This is the temperature gradient of the temperature detected by the temperature sensor in contact with the bottom of the pot (temperature rise rate per unit time)
When the temperature gradient becomes equal to or less than a predetermined value, the temperature is determined to be boiling, and the detected temperature at that time is set as the boiling temperature, and when the detected temperature rises by a predetermined temperature or more from this temperature, the heating is performed. It will stop.

[0003] However, the temperature detected by the temperature sensor in contact with the bottom of the cooked dish changes as shown in FIG. 3 due to the adjustment of the heating power after boiling, in addition to the case where the water evaporates. Nevertheless, in the above technique, the reference temperature for fire extinguishing is kept at the boiling temperature detected first, so that there is a problem that fire extinguishing at an appropriate temperature cannot always be obtained. For this reason, in the technique of Japanese Patent Application No. 3-145647 previously submitted by the present applicant, the detection temperature when the rate of increase of the detected temperature becomes equal to or higher than a predetermined value after the detection of the boiling point is set to the inflection point. The heating is stopped when the detected temperature rises from the bending point by a predetermined temperature or more. According to this technique, the temperature at the time when the temperature starts to rise due to the disappearance of moisture is used as the fire extinguishing criterion, so that the automatic fire extinguishing temperature for preventing burning is more appropriate.

[0004]

However, according to the technique disclosed in Japanese Patent Application No. 3-145647, when a low heat is applied as shown in a range C in FIG. Before the rising detection temperature reaches the boiling temperature Td in the range D, the detection temperature T reaches the extinguishing point L which is above the inflection point TTb by a predetermined value (Δb1), and automatically extinguishes the fire by erroneously recognizing that it is burnt. There is a problem that there is.

[0005] In addition, in cooking cooked dishes, a pot is sometimes lifted from a cooker and shaken (hereinafter simply referred to as a pot shake) in order to stir the contents well during cooking. Since the sensor is separated from the bottom of the pot and heated by the high-temperature atmosphere of the cooker, the detected temperature sharply increases. For this reason, there is an inconvenience that the fire extinguishing temperature is reached in the middle of the pan swing and automatic fire extinguishing is performed.

An object of the present invention is to solve these problems and improve the usability of a cooker equipped with this type of automatic fire extinguishing device.

[0007]

For this purpose, an automatic fire extinguisher for a cooker according to the present invention comprises, as shown in FIG. 1, a temperature sensor 35 for detecting the temperature of a cooking utensil such as a pot.
In an automatic fire extinguisher for cookers comprising a heating stop means 1 for stopping the operation of a heating means 10 for heating the cooking utensil based on the temperature detected by the temperature sensor, a unit time based on the temperature detected by the temperature sensor 35 A temperature gradient calculating means 2 for calculating a temperature rise rate per contact; a boiling point detecting means 3 for detecting a boiling point based on a temperature detected by the temperature sensor 35; and a highest among a plurality of boiling points detected by the boiling point detecting means 3. And a maximum boiling point storage means 4 for storing the maximum boiling point as a maximum boiling point, and when the temperature rise rate calculated by the temperature gradient calculating means 2 after the boiling point detection by the boiling point detecting means 3 becomes equal to or higher than a predetermined value. The inflection point detecting means 5 for detecting the temperature detected by the temperature sensor 35 as an inflection point, and the maximum boiling point stored in the maximum boiling point storage means 4 are predetermined. Fire extinguishing temperature setting means for setting a higher temperature to a fire extinguishing temperature among a value obtained by adding a predetermined value and a value obtained by adding a second predetermined value to a bending point detected last by the bending point detecting means 5. 6, the heating stopping means 1
When the detected temperature of the temperature sensor 35 exceeds the fire extinguishing temperature set by the fire extinguishing temperature setting means 6, the operation of the heating means 10 is stopped.

It is preferable that the second predetermined value is set to a large value if the temperature rising speed calculated by the temperature gradient calculating means 2 is high.

[0009]

The temperature gradient calculating means calculates the temperature rise rate per unit time based on the temperature detected by the temperature sensor.
The boiling point detecting means 3 detects the boiling point based on the detected temperature. In the case where the thermal power is adjusted after boiling, a plurality of different values are obtained at a time interval. The highest boiling point storage means 4 stores the largest one among the plurality of detected boiling points detected as described above as the highest boiling point. on the other hand,
The inflection point detecting means 5 detects the temperature gradient after the boiling point is detected.
The detected temperature of the temperature sensor 35 when the temperature rising speed calculated by the above becomes equal to or more than a predetermined value is detected as a bending point. The fire-extinguishing temperature setting means 6 determines a value obtained by adding a first predetermined value to the maximum boiling point stored in the maximum boiling point storage means 4 and a bending point detected last by the bending point detecting means 5. The higher temperature of the value obtained by adding the second predetermined value is set as the fire extinguishing temperature, and the heating stop means 1 stops the operation of the heating means 10 when the temperature detected by the temperature sensor 35 exceeds the fire extinguishing temperature.

[0010] Since the temperature of the bent point detected by the bending point detecting means 5 becomes high when moisture evaporates in a cooked product heated over a high or medium heat, the second predetermined value is usually added to the bending point. The value obtained is the fire extinguishing temperature, and the cooked product heated by low heat may have a lower detected inflection point temperature. In this case, the value obtained by adding the first predetermined value to the maximum boiling point is better. Fire extinguishing temperature. When a cooked product that has been heated with a low heat is heated with a high heat close to the maximum, the temperature detected by the temperature sensor 35 may rise to the maximum boiling point or slightly higher, but the first boiling point is set to the maximum predetermined value. Will not be higher than the value added, so that automatic fire extinguishing is not performed by mistakenly as burning.

According to the second aspect of the present invention, in the case of pan swinging, the temperature rise speed becomes faster, so the second predetermined value for determining the fire extinguishing temperature based on the inflection point is a large value. Therefore, the temperature detected by the temperature sensor 35 rises rapidly during the shaking of the pan,
In this case, the fire extinguishing temperature becomes higher by the large second predetermined value, so that the detected temperature does not exceed the fire extinguishing temperature.

[0012]

As described above, according to the present invention, when a cooked product that has been heated with a low heat is heated with a high heat close to the maximum, it is not erroneously recognized as burnt and automatic fire extinguishing is not performed. It is possible to improve the usability of a cooker provided with a kind of automatic fire extinguishing device.

According to the second aspect of the present invention, since the detected temperature does not exceed the extinguishing temperature in the course of shaking the pot, automatic extinguishing does not occur, and the usability of this type of cooker can be further improved. .

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the embodiments shown in FIGS. FIG. 2 is a sectional view of a main part of an embodiment in which the automatic fire extinguisher for a cooker according to the present invention is applied to a table stove. A gas burner 10 (heating means) composed of a burner main body 11 and a burner head 12 is fixed to a casing (a part of which is indicated by reference numeral 13), and a cooking utensil 15 such as a pot is provided thereon via a gotoku (not shown). It is put on. Burner head 12
A temperature sensor 35 such as a thermistor is provided at the upper end of the movable cylinder 14 supported by the casing 13 so as to be able to ascend and descend through a central portion of the pan. When the movable cylinder 14 is raised as shown in FIG. 15 is elastically pressed against the bottom surface by a spring. An ignition plug 36 and a flame sensor 37 such as a thermocouple or a frame rod are fixed to the casing 13.

The valve casing 20 of the gas valve device includes a casing 13
The fuel gas from the gas inlet 20a is supplied to the gas burner 10 via the valve body 25a of the solenoid valve 25 and the closing member 21 rotated by the operation knob 24. When the operation knob 24 is rotated from the closed state, the micro switch 26 is first activated, and as the operation knob 24 rotates, the
Of the valve stem 23, and finally the valve stem 23 via the cam device 22.
Is moved to push and open the valve body 25a of the electromagnetic valve 25 which is normally closed by a spring, and the movable cylinder 14 rises in conjunction with this.

The burner controller 30 comprises a central processing unit (CPU) 31, a read-only memory (ROM) 32, and a writable memory (RA) which constitute a well-known logical operation circuit.
M) 33 and an interface 34 as main components, a control program for automatic fire extinguishing described later and various fixed constants are stored in a ROM 32, and a temperature gradient (per unit time) detected as described later is stored in a RAM 33. Temperature, the detected boiling point, the maximum boiling point TM, the inflection point TT, the fire extinguishing temperature, and other data during arithmetic processing. The control program for automatic fire extinguishing includes a value obtained by adding a predetermined first predetermined value Δa to the maximum boiling point TM and a predetermined second predetermined value Δb1 (or Δb2) to the last detected bending point TT. The program includes a program for extinguishing the heating means 10 when the temperature detected by the temperature sensor 35 exceeds the extinguishing temperature. The interface 34 converts the input signal from the temperature sensor 35 and the like into C
The signal is converted into a signal that can be calculated by the PU 31 and the CPU
The output signal from the controller 31 is converted into an output signal capable of driving the electromagnetic valve 25 and the like. Via the interface 34, the electromagnetic valve 25, the microswitch 26, the temperature sensor 35, the ignition plug 36, and the flame sensor 37 are connected. It is connected to the CPU 31.

Next, the operation of the above embodiment will be described. First, when the operation knob 24 is manually rotated, the micro switch 26 is operated to turn on the power of the burner controller 30, and the movable cylinder 14 is raised, and the temperature sensor 35 is pressed against the bottom surface of the pot 15, and is further rotated. The opening degree of the closing member 21 increases, and finally the valve body 25 a of the solenoid valve 25 is opened by being pushed by the valve rod 23, and the fuel gas is supplied to the gas burner 10. At the same time, an igniter (not shown) is activated and the spark plug 36 generates a spark, ignites the gas ejected from the gas burner 10 and generates a flame for heating the pot 15 such as cooked food.
When the flame sensor 37 detects this flame, the burner controller 30 stops the operation of the ignition device and supplies a current to the solenoid valve 25. If you release your hand in this state, the operation knob 24
Although the valve rod 23 is slightly returned elastically and the valve rod 23 is separated from the valve body 25a, the valve body 25a is kept open by the current to the solenoid valve 25, and the fuel gas to the gas burner 10 is continuously supplied. In this state, the closing knob 2 is operated by the operation knob 24.
The heating amount of the gas burner 10 is adjusted by adjusting the opening degree of the gas burner 10.

4 to 6 are flowcharts showing a control program for automatic fire extinguishing. FIG. 4 shows a main routine, and FIGS. 5 and 6 show first and second subroutines, respectively. The automatic fire extinguishing control process executed by the burner controller 30 will be described with reference to this flowchart. When the power of the burner controller 30 is turned on, the CPU 31 resets each data in the RAM 33 to 0 or a predetermined initial value, and executes the control operation according to the flowcharts of FIGS.

First, a description will be given of a normal case where the table stove is started from a cold state and the detected temperature T of the temperature sensor 35 changes as shown in FIG. In the state of range A immediately after the start of heating, boiling detection is not performed until the detected temperature T reaches 80 ° C. (step 101). The temperature detected by the temperature sensor 35 exceeding 80 ° C. is the first boiling point TB (= T
When the temperature reaches a, for example, 130 ° C.), the CPU 31 detects the boiling (step 102 and steps 201 and 205 to 207 of the first subroutine). The detection of the boiling is performed, for example, by using the detection data of the temperature sensor 35 stored at intervals of 15 seconds, the CPU 31 compares the temperature data of one minute and two minutes ago with the current temperature data, and compares the difference. Are determined to be boiling when both are within ± 2 ° C. In detecting the boiling, the CPU 31 calculates the temperature rising speed (temperature gradient) of the detected temperature T based on the detection data of the temperature sensor 35 stored as described above, and the temperature gradient is set to a predetermined range around 0. If the temperature falls within the range, it may be determined that the water is boiling. Next, the highest boiling point TM (= Ta) is stored in a predetermined storage area of the RAM 33 (steps 103 to 107).

If the thermal power is increased by opening the closing member 21 with the operation knob 24 from the state of the range A, the detected temperature T rises as shown in FIG. 3 and the next detected boiling point TB (= Tb, for example, 14)
0 ° C). At the beginning of this ascent, the CPU 31
Tb is detected (step 106). The detection of the bending point TTb is based on the detection data of the temperature sensor 35, when the state that the detected temperature T rises by 2 ° C. within 30 seconds occurs three times in succession, the last detection point (ie, 6 ° C.) The rise point) is defined as the inflection point TTb. After detecting the inflection point TTb, the detected temperature T further rises and enters the range B, and the boiling point Tb
And boiling is detected (step 301 of the second subroutine, steps 305 to 307). And the highest boiling point
TM stores the detected boiling point TB higher than the detected boiling point Ta.
(= Tb) (steps 103 to 107). In a normal use state, the temperature gradient of the detected temperature T is not 50 ° C./min or more, so the second predetermined value is a low value Δb1 (eg, 15 ° C.), but the temperature difference between the detected boiling points Ta and Tb is less than Δb1. Therefore, the detected temperature T does not reach the aforementioned fire extinguishing temperature,
Therefore, the gas burner 10 is not extinguished.

Next, if the thermal power is reduced by greatly squeezing the closing member 21 in order to carefully cook the stew, the detected temperature T falls and enters the range C, and the value of the detected boiling point TB becomes Tc (for example, 11 ° C.).
0 ° C.) (steps 104 to 107). During this downward movement, the boiling point TB remains at Tb (= TM), and the boiling point TB (= Tc) detected after entering the range C is less than the maximum boiling point TM, so that the maximum boiling point TM is not updated.

If the thermal power is greatly increased by opening the closet 21 to or near the fully opened state from the range C, the detected temperature T
Increases into the range D, and the value of the detected boiling point TB becomes Td (for example, a value slightly higher than the detected boiling point Tb). As in the case of the range B, the CPU 31 detects the inflection point TTd at the beginning of the ascent (step 106). After detecting the inflection point TTb, the detected temperature T
Further rises into the range D, reaches the detection boiling point Td, and detects boiling (step 301, steps 305 to 30).
7). Also in this case, since the temperature gradient of the detected temperature T does not exceed 50 ° C./min, the second predetermined value is a low value Δb1,
The temperature difference between the detected boiling points Tc and Td is larger than the second predetermined value Δb1. However, the detected boiling point Td does not become much higher than the highest boiling point TM (= Tb), and the first predetermined value Δ
a (for example, 10 ° C.). Therefore, similarly to the case of the above-described range B, the detected temperature T does not reach the above-described extinguishing temperature, and the gas burner 10 is not extinguished. Since the detected boiling point Td is higher than the detected boiling point Tb,
The stored content of the maximum boiling point TM is updated to the detected boiling point Td (steps 103 to 107).

If the heating power is reduced again, the detected temperature T falls and enters the range E, and the value of the boiling point TB becomes Te close to Tc.
The operation in this case is the same as in the case of the above-described range C, and the value of the maximum boiling point TM is not updated while remaining at Td.

In this state, the stew is continued, and if the water evaporates, the detected temperature T starts to rise. However, also in this case, the temperature gradient of the detected temperature T does not become 50 ° C./min or more, and the detected temperature T rises as shown by the solid line in the range F. At the beginning of this rise, the CPU 31
Detects the bending point TTf (step 106). In this state, the value obtained by adding the first predetermined value Δa to the highest boiling point TM and the value obtained by adding the second predetermined value Δb1 to the last detected bending point TT (= TTf) are the former as shown in FIG. Is higher, so the former is the extinguishing temperature. When the detected temperature T rising along the solid line of FIG. 3 reaches a point M where TM + Δa, the CPU
31 stops supply of current to the solenoid valve 25, and the valve body 25a
Is closed to stop the operation of the heating means 10 (step 3
01, steps 305 to 307, 112). If the detected boiling point Te immediately before the evaporation of water was high, TTf +
Δb1 is the fire extinguishing temperature.

When the pot is shaken in the range E in FIG. 3, the temperature gradient of the detected temperature T increases to 50 ° C./min or more, and the detected temperature T rises as indicated by the two-dot chain line in the range E. The second predetermined value is a high value Δb2 (for example, 35 ° C.). In this case, the value obtained by adding the first predetermined value Δa to the highest boiling point TM and the value obtained by adding the second predetermined value Δb2 to the last detected bending point TT (= TTf) are higher. Becomes the extinguishing temperature.
Then, the detected temperature T rising along the two-dot chain line in FIG.
When the point N reaches Tf + Δb2, the CPU 31 stops supplying the current to the solenoid valve 25, closes the valve body 25a, and stops the operation of the heating means 10 (step 30).
1, steps 315 to 317, 112). However, since the second predetermined value Δb2 is larger, the detected temperature T does not reach the point N during the normal pan swing time, and therefore, automatic fire extinguishing is not performed.

As described above, according to this embodiment, in many cases (especially when the detected boiling point is high at that time), the temperature at the inflection point TT at which the temperature has started to rise due to the disappearance of water is determined as the fire extinguishing temperature. As it becomes the standard, when the automatic fire extinguishing temperature for preventing burning is appropriate, and the cooked boiled dish that has been heated over low heat is suddenly heated with high heat close to the maximum,
Since there is no automatic fire extinguishing by mistakenly as a scorch and no automatic fire extinguishing in the middle of pan swing, the usability of a cooker equipped with an automatic fire extinguishing device can be improved.

Since boiling detection is not performed in the case of a grilled dish, when the cooking device of the present embodiment is used for a grilled dish, it mainly operates in the first subroutine, and the temperature is set to a predetermined temperature or higher. Fire will be extinguished. In this case, the detected temperature T of the temperature sensor 35 is 140 ° C.
The temperature rise time between 150 ° C and 150 ° C is detected.
If it is less than one minute (the temperature gradient is large), the fire is extinguished at 200 ° C. (step 202, steps 205 to 208), and if this time is 2 minutes or more (the temperature gradient is small), the fire is extinguished at 170 ° C. (step) 202, steps 215 to 218).

In the case where the inflection point TT is not detected after the boiling detection is performed, such as in a curry dish, but the temperature rises slowly, the fire is extinguished if the temperature exceeds a predetermined temperature (steps 107 to 111, 112). ). In this case, the boiling point TM detected in step 102 is 130 ° C.
150 ° C if below, 170 if boiling point TM is below 150 ° C
Extinguish at ℃, otherwise 190 ° C.

When the temperature T detected by the temperature sensor 35 drops by 10 ° C. or more within 30 seconds, for example, when the pot 15 is removed and the temperature is lowered, the process returns to step 102 to detect the boiling again. (Step 1
05, step 306, step 316).

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an automatic fire extinguisher for a cooking appliance according to the present invention.

FIG. 2 is a view showing a main part of an embodiment of an automatic fire extinguisher for a cooker according to the present invention.

FIG. 3 is a diagram illustrating an operation state of the embodiment of FIG. 2;

FIG. 4 is a flowchart of a main routine of a control program according to the embodiment of FIG. 2;

FIG. 5 is a flowchart of a first subroutine that forms part of the main routine of FIG. 4;

FIG. 6 is a flowchart of a second subroutine that forms a part of the main routine of FIG. 4;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Heating stop means, 2 ... Temperature gradient calculating means, 3 ... Boiling point detecting means, 4 ... Maximum boiling point storing means, 5 ... Bending point detecting means,
6 ... fire extinguishing temperature setting means, 10 ... heating means (gas burner), 35 ... temperature sensor.

Claims (2)

(57) [Claims] 1. A temperature sensor for contacting and detecting the temperature of a cooking utensil such as a pot, and a heating stop unit for stopping the operation of a heating unit for heating the cooking utensil based on the temperature detected by the temperature sensor. In the automatic fire extinguisher for cooking appliances, a temperature gradient calculating means for calculating a temperature rise rate per unit time based on the temperature detected by the temperature sensor, and a boiling point detecting means for detecting a boiling point based on the temperature detected by the temperature sensor, A maximum boiling point storage means for storing the highest one of the plurality of boiling points detected by the boiling point detection means as a maximum boiling point; and a temperature rise rate calculated by the temperature gradient calculating means after the boiling point detection by the boiling point detection means. A bending point detecting means for detecting a temperature detected by the temperature sensor when the temperature becomes equal to or more than a predetermined value as a bending point; and a maximum boiling point storage means. The higher of the value obtained by adding a predetermined first predetermined value to the determined maximum boiling point and the value obtained by adding a predetermined second predetermined value to the bending point detected last by the bending point detecting means. Fire extinguishing temperature setting means for setting the extinguishing temperature, wherein the heating stop means stops the operation of the heating means when the temperature detected by the temperature sensor exceeds the extinguishing temperature set by the extinguishing temperature setting means. Automatic fire extinguisher for cookers. 2. The automatic fire extinguisher according to claim 1, wherein the second predetermined value is set to a large value if the temperature rising speed calculated by the temperature gradient calculating means 2 is high.